Riverside International Raceway (sometimes known as RIV, RIR, or Riverside Raceway) was a race track or road course in Riverside, California. The track was in operation from September 22, 1957, to July 2, 1989. The original course design proved to be dangerous, and it was partially reconfigured in 1969.

The track was built to accommodate several different configurations, depending on the type of car and race length. The three options on Riverside Raceway were the long course (3.27 miles (5.26 km)), the short course (2.5 miles (4.0 km)), and the NASCAR (2.62 miles (4.22 km)) course. The original racetrack had a 1.1-mile (1.8 km) backstretch from 1957 to 1968. When the track was redesigned in 1969, Turn 9 was reconfigured with a wider radius and a dogleg approach added to reduce strain on the cars' brakes.

Before a racing event at RIR, track crews added traffic pylons to close off sections of the track. Track courses are shown in the illustrations below (the 1957 course is in black, while the 1969 course above is in blue).

Diagram notes: The long course (shown below before the 1969 version) had the 1.1-mile (1.8 km) backstretch. This version was used primarily for the track's signature fall sports car event, the Los Angeles Times Grand Prix, although the long course was also used for IndyCar racing in the mid-1980s. When the 1969 version was built, the dogleg was added so as to ease the transition into Turn 9 (the track had seen numerous brake failure-induced accidents approaching Turn 9, and this change was made as a safety measure). The NASCAR course, 1st design on the right (light blue illustration), would not use turn 7. In the short course, the track would use turn 7A rather than 8. The "Turn 7-7A" configuration effectively shortened the back straight to just over one-half mile in length. The NHRA drag strip only used the backstretch from the runoff to the Bosch Bridge. The Oval marked in gold (early '60s) used Turn 9, ran counterclockwise, uphill for Turn 1 & 2 and then there was a downhill turn for Turn 3 & 4 (Between the backstretch and Turn 1 of the road course).

Riverside Raceway back from 1957 to 1968, complete with the 1.1-mile backstretch

1969 to 1989 version of Riverside Raceway, the 1957 to 1968 version is shown beside it

The first weekend of scheduled races in September 1957, a California Sports Car Club event, John Lawrence of Pasadena, California, lost his life. Lawrence, a former Cal Club, under 1500 cc Production champion, went off at Turn 5 (later designated Turn 8). With no crash barrier in place, and no rollbar on the car, the MG A he was driving went up the sand embankment, then rolled back onto the track. Though Lawrence survived the incident, and appeared slightly injured, he died later at the hospital of a brain injury.

The second major event at the track, in November 1957, was a sports car race featuring some of the top drivers of the day, including Carroll Shelby, Masten Gregory and Ken Miles. Another driver entered was an inexperienced local youngster named Dan Gurney, who had been offered the opportunity to drive a powerful but ill-handling 4.9-liter Ferrari after better-known drivers such as Shelby and Miles had rejected it. Shelby led early but spun and fell back. Gurney assumed the lead and led for much of the event. Shelby, driving furiously to catch up, finally overtook Gurney late in the race and won. Gurney's performance caught the eye of North American Ferrari importer Luigi Chinetti, who arranged for Gurney to drive a factory-supported Ferrari at Le Mans in 1958, effectively launching the Californian's European career.

The track was known as a relatively dangerous course, with its long, downhill back straightaway and brake-destroying, relatively slow 180-degree Turn 9 at the end. During the 1965 Motor Trend 500 NASCAR race, Indycar great A.J. Foyt suffered a brake failure at the end of the straight, going end-over-end at high speed. Crash crews assumed Foyt was dead at the scene, until fellow driver Parnelli Jones noticed a twitch of movement. Ford factory sports car driver Ken Miles was killed there in a testing accident in August 1966 when his Ford sports car prototype (known as the J-car) became aerodynamically unstable and flew out of control at the end of the back straight. In December 1968, American Formula 5000 champion Dr. Lou Sell crashed and overturned in Turn 9 on the first lap of the Rex Mays 300 Indianapolis-style race, suffering near-fatal burns. These accidents and others caused track management to reconfigure Turn 9, giving the turn a dogleg approach and a much wider radius (a water improvement also closed the raceway for a few months).

In January 1964, Riverside also claimed the life of 1962–'63 NASCAR champion Joe Weatherly, who refused to wear a shoulder harness and wore his lap belt loosely. Weatherly died when he lost control entering Turn 6, hitting the steel barrier almost broadside and had his head snapped out the window against the barrier.

Nevertheless, in 1983 Turn 9 was the site of the only fatality in IMSA GTP history. In the 1983 Times Grand Prix, Rolf Stommelen's Joest-constructed Porsche 935 lost its rear wing at the Dogleg and hit two freeway-type barriers sending it into a horrific roll at Turn 9.

When the racetrack was proposed in the mid-1950s, Riverside International Motor Raceway (as it was called at the time) was planned to ultimately be 5.0 miles (8.0 km) long, but the club extension was never constructed and the track's final length (after Turn 9 was adjusted in 1969, engineered by David Berg, to a 10 degree banked sweeper) was 3.3 miles (5.3 km).

Of the entire road course races run at RIR, there was at least one that was run in a counter-clockwise direction sometime in the 1960s. In the spring of 1966 Dan Gurney tested his first Eagle racing car on a shortened, counter-clockwise version of the track (to accommodate the car's Indianapolis-specific left-turn oiling system). The test led Gurney to propose to track president Les Richter to hold an Indianapolis-style race there. The Rex Mays 300 served as the season-ending USAC Indianapolis-car race from 1967 to 1969.

ESPN taped the June 12, 1988, Budweiser 400 race at RIR and caught racer Ruben Garcia crashing hard off turn 9 and his car went through two cement barriers before coming to rest near a catch fence where fans were sitting. He was not injured, though, and neither were the race fans.

From 1981 until 1987, NASCAR's championship race was at Riverside. The USAC Championship Trail also held their season ending race from 1967 to 1969.

Riverside was home to track announcer Sandy Reed and (along with former LA Rams player Les Richter) Roy Hord Jr.

NASCAR Team owners Roger Penske and Rick Hendrick drove a select few races at Riverside in their own cars. Penske won a Winston West race in 1963, while In the final race in 1988, Hendrick got out of the car and let Elliott Forbes-Robinson take over.

Riverside's Winston Western 500 was the opener to the NASCAR Winston Cup season until 1981, when NASCAR moved the start of the season to February and changed the starting race to the Daytona 500. That same race was moved to the end of the year and became the season finale for the Cup Series, a distinction it held until 1986.

There are two streets in the neighborhood to the east of the Moreno Mall, Andretti Street and Penske Street, a reference to Mario Andretti, and Roger Penske a driver and team owner who each won multiple races at Riverside.

A shot of RIR in 1989 during the transformation from racetrack to shopping mall, note the new section of pavement for racing to continue

RIR, headed by former Los Angeles Rams player Les Richter sold the property to real estate developer Fritz Duda in 1983. The irony is that Duda had once been a turn announcer for NASCAR's broadcasting arm Motor Racing Network, and many felt racing would long be a part of the Riverside landscape. 1988 was the final year of racing for Riverside International Raceway. On June 12, 1988, NASCAR held its final race at RIR – a race won by Rusty Wallace (a caution flag was out for Ruben Garcia when he came off Turn 9 and lost control of his car and hit a wall, missing the grandstands). In 1989, the track was modified from turn 7A to the back straight. The modified track was called Riverside Regional Raceway and continued to be used for club events. After SCORE International held its last race, the track finally closed its gates after 32 years of racing. Fritz Duda turned the "House that Dan Gurney built" into a shopping mall which opened in 1992. The Moreno Valley Mall at Towngate is on the northern end of the former raceway property and houses now occupy the southern end of the old racetrack (where Tim Richmond and Dale Earnhardt raced). In a 1994 topographical map, the remains of Riverside's Turn 9 and a wall were still visible. However, today nothing is left of RIR except for memorabilia from the racetrack. The old Administration Building remained until 2005, when it was torn down to make way for a complex of townhomes.

In 2003, the remainder of the old Riverside International Raceway was torn up. The sign that was at California 60 and Day Street was removed to make way for a Lowe's warehouse and Turn 9 of the old track is now home to houses.

In 2003, plans were announced to build a 3-mile (4.8 km) road course with a similar design to the famed Riverside layout in Merced, California. The track would have been known as the Riverside Motorsports Park, but the project was abandoned in 2009.[3]